Safety is a prime concern for the aviation industry. Although flying is very safe from a statistical standpoint, any crash involving even private aircraft receives extensive attention from the Government and from the news media. The crash of a commercial airliner often brings with it the loss of many lives and so attracts even more attention.
Although many aids have been developed that act to improve aircraft safety, the most important safety factor in flying is an attentive pilot who pays careful attention to his surroundings while in the air and on the ground. Chief among the factors that help an attentive pilot to observe his surroundings is good visibility. When clouds or fog obscure visibility, then a pilot's choices are either to avoid flying in the clouds or fog or to rely on navigational instruments under the terms of instrument flight rules (IFR). On many days, however, in many parts of the United States, visibility is impaired, not by clouds or fog, but by smoke, dust, vapor, and moisture that accumulate in the atmosphere. This accumulation is often referred to as haze. Haze is most evident in urban areas having geographical factors that tend to trap haze or smog. However, atmospheric conditions even in rural areas of the central United States lead to haze formation that obscures the horizon during much of the summer. Generally, haze is an element that nearly always must be considered as a factor in evaluating visibility for pilots.
The presence of haze especially impacts the safety of flying in the vicinity of airports. Airports mostly are located near urban areas where haze is already a factor. Of course, air traffic tends to concentrate around airports. Exhaust from aircraft is one of the components of haze. Increasing haze decreases pilot visibility. Decreasing pilot visibility further increases the risk of mid-air collision, a critical safety concern. Aside from the risk of mid-air collision, haze also acts to reduce the ability of a pilot to identify landmarks. Identifying landmarks is an important part of air navigation, especially for pilots flying under visual flight rules (VFR).
It should be clear that anything that can be done to decrease the negative effects of haze would directly increase the safety of flying. This safety improvement would accrue to the benefit of both commercial and general aviation.
The prior art has not effectively addressed methods for decreasing the visual effects of haze. Most effort in this area has been aimed at improving hardware. For example, infrared imaging hardware with enhanced haze penetration capabilities has been developed. However, infrared imagers are quite costly. Infrared imagers also employ reduced picture element (pixel) array sizes that limit achievable resolution. These devices also suffer from associated drawbacks such as fog self-radiation. Ground moisture also can induce a loss of image thermal contrast that reduces the effectiveness of infrared imagers.